Circulating gaseous medium through rotating drums



Maich 17, 1959 E. 'KRANTZ 2,877,562

CiRCULATING GASEOUS MEDIUM THROUGH ROTATING DRUMS Filed June-26, 1956 oi I I w F114 *1 v x #1:1: :11....Juuuu!!!% m H Q: I

INVENTORI EVERT KRANTZ ATTYS States 'CIRCULATING GASEQUS MEDIUM THROUGH ROTATHNG DRUMS Evert Krantz, Stockholm, Sweden, assignor to AB Svenska Flaktfabriken, Stockholm, Sweden 2 Claims. (Cl. 34-29) The present invention relates to a method for the supply and discharge of a gaseous treating medium in rotating drums, used for treating pulverulent and granular materials. The drums consist of a substantially horizontal unperforated cylinder, rotatably supported between two stationary end sections, provided with feeding and discharge openings respectively for the material. During the rotation of the drum by means of lifting means arranged on the inside of the cylindrical wall of said drum, the material is forced to move helically and is tumbled from the feeding end to the discharge end and thereby is subjected to the action of the circulating treating medium.

In treating materials in the above manner it has often proved difiicultespecially by the treating of materials having a low density-to supply the treating medium in sufficient quantities and in such a manner that an intimate contact is obtained between the medium and the material. it is diflicult at the same time to eliminate disadvantageous leakage at the feeding and discharge ends and disturbance of the feeding and discharge of the material and the transport of same through the drum by the medium currents.

It is a main object of the invention to eliminate said disadvantages. The method according to the invention is characterized in that the gaseous treating mediumis supplied to the drum at both the feeding and discharge ends but is exhausted only at the discharge end of the drum, whereby the treating medium supplied at the feeding end is introduced into the drum together with the material by being injected into the flow of material peripherically and with an ejecting effect of the material, whereas the medium supplied at the discharge end is introduced as a number of medium jets directed inwardly of the drum and acting along the cylindrical wall in one of the upper quadrants of the drum.

A suitable apparatus for the performance of said method consists of a substantially horizontal unperforated cylinder, rotatably supported between two stationary end sections, provided withfeeding and discharge openings respectively for the material, and means for conditioning and circulating a gaseous treating medium. The apparatus is characterized by a chamber for the supply of treating medium, said chamber encircling the inlet tube for the material at the feeding end and communicating therewith through one or more annular slots in the inlet tube and constituted by the intermediate spaces between two or more parts of said tube, somewhat projecting one into the other and of increasing cross sections reckoned in the flow direction of the fed material and a second medium supply chamber arranged in the upper part of the stationary end section at the discharge end and provided with a number of medium supply nozzles projecting towards the drum adjacent the periphery of the drum in one of its upper quadrants, and lastly a third chamber for the exhaustion of the treating medium, said third chamber being arranged in the upper part of the stationary section at the discharge end and situated behind said atent second chamber for the medium supply and provided with a perforated lower side wall facing the bottom of the drum.

The invention will now be described more in detail with reference to the accompanying drawing, in which:

Fig. 1 is an elevational view partly in section showing one embodiment of apparatus made in accordance with the present invention; and,

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1.

In the drawing 1 designates a drum consisting of a substantially horizontal unperforated cylinder. The drum is rotatably supported between two stationary end sections 2, 3. The drum is during the rotation supported by two pairs of bearing rolls 4. 5 designates the feeding opening for the material and 6 designates the discharge opening for same. 7 designates a number of lifting means arranged on the inner side of the cylinder. 8 designates means for conditioning a gaseous treating medium, which is circulated through the drum by means of a fan 9. In the illustrated embodiment, where the drum is used for humidifying a relatively light material, for instance tobacco, the conditioning means 8 consists of a device for supplying water to the treating medium and a device for separating water drops. Said means can, however, be modified to correspond with the intended treatment in the drum. 10 designates a chamber for the supply of treating medium. This chamber encircles the inlet tube for the material at the feeding end and communicates therewith through one or more annular slots 12 in the inlet tube. The slots are constituted by the intermediate spaces between two or more parts 13, M, 15 of said tube, somewhat projecting one into the other and of increasing cross sections reckoned in the flow direction of the material. The central part 14 is mounted in the chamber 10 by means of a spider or supporting rods (not shown). 16 designates a second medium supply cham-, ber, which is arranged in the upper part lb of the stationary end section. Said chamber is provided with a number of medium supply nozzles 17. a chamber for the exhaustion of the treating medium. Said chamber is arranged in the upper part of the end section at the discharge end and is situated behind said second chamber for the medium supply and is provided with a perforated lower side wall 19, facing the bottom of the drum.

What I claim is:

1. Apparatus for treating pulverulent and granular materials by means of a circulating treating medium comprising a substantially horizontal, rotatable drum having an axial passageway from one end to the other for the material to be treated therein, a stationary feeding end section having a tube-like chute passing from the outside for introducing the material into said drum, said chute having a cross sectional area increasing in the direction of feed of the material and consisting of at least two aligned tubular elements, each element projecting into the succeeding element and having a cross sectional area smaller than the bore of the succeeding element, the intermediate space between said parts of the chute forming at least one annular slot in said chute, a stationary discharge end section provided with an outlet for treated material, a chamber for supplying treating medium at the feeding end of the drum, said chamber surrounding said chute and communicating therewith through said annular slot, a second medium supply chamber mounted in the upper part of the stationary discharge end section, a plurality of ,medium supply nozzles mounted in said second chamber and projecting toward the drum adjacent the periphery thereof in one of the upper quadrants thereof, a third chamber for exhausting the treating 1S designates 3 medium mounted in the upper part of the stationary discharge endsec'tion behind said second chamhensaid third chamber having a perforated lower wall facing the bottom of.v the drum, and means for circulating the treating mediumv through said drum by introducing themedium through said first and second chambers and exhausting thesamethrough said third chamber. I a

2. Indie method of treating pulverulent and granular materials by 'a gaseous treating medium in a rotating drum havingl at its opposite ends feeding and discharge openings respectively for the material, and in which the material is flowed into the drum andthe n is tumbled and caused to "move helically from the feeding end to the discharge end. while being subjected to the action of the circulating treating medium in said drain, the steps of supplying the gaseous treating medium to the drum from a s'our'ce, dividing said medium into two individual streams and simultaneously introducing them into the drum at opposite ends of the same by injecting the medium stream supplied at the feeding end of the drumperipherally around the entering flow of material being fed into the drum to cause an injecting force acting upon said material, and injecting the other medium stream at the discharge end of the drum into the'helically moving material at the periphery thereof in ,form of jets directed countercurrent to the movement of material, and exhausting all of said treating medium at the discharge end of the'drum beyond the point of injection of said second medium stream.

References Cited in the file of this natent UNITED STATES PATENTS 1,545,055 Lindhard July 7, 1925 2,276,589 Peltier et al Mar. 17, 1942 2,543,776 Greisen Mar. 6, 1951 

